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Bright will have two rings of LEDs driven by a microcontroller. An ambient light sensor will adjust the brightness of the digital flame on the fly. Two buttons on the bottom will control the power and toggle between modes.
The entire setup will be powered by a 20mm coin cell battery.
I recently got a message from a 'community manager' at hackaday.io requesting that I post more pictures of bright. I threw together a rough prototype on a breadboard with an arduino pro mini, but ultimately didn't want to post pictures of it. I wanted something impressive-looking that would attract attention (and skulls) to my project. So, I took a couple hours out of a rainy day to assemble a 'dead bug' freeform circuit that would more or less be electrically similar to the final version of bright. I used an attiny85 because I already have a few of those on hand. It's my first attempt at deadbug style design, and while the main reason I built it was lack of any protoboard, I have to say it looks very cyberpunk-ish and intriguing.
I'm crossing my fingers that it will work, given that I didn't even test out the schematic beforehand to make sure everything was OK, nor have I written a single line of code. However, the hardware will be the easy part of this project-it's essentially a fancy blinkinlight, but the software is going to take a little while. I'll have to do a quick sketch in arduino before porting the code over to GCC and optimizing it to take up as little space as possible while still looking like a semi-realistic candle.
The schematic is above. I didn't feel like spending another half hour on EAGLE so I sketched out a rough draft on paper in 5 minutes. The thing on the left is my attempt at drawing an LDR (I don't know what the symbol is). I probably won't be making very fast progress on this project; I'm working on a paid freelance job while working fast to finish up #bioloop, all before school starts.
I searched around for small, low cost microcontrollers that would be ideal LED candle drivers. At the very least, I needed something with 5 i/o pins, including one ADC pin for a light sensor. It was tempting to pick something from the tiny*5 family, simply because the Arduino IDE support is so good, but it would come at a cost in terms of volume production.
| Name | price/1 (USD) | price/1K (USD) |
| MSP430G2131 | 1.51 | 0.55 |
| STM32F030 | 1.37 | 0.62 |
| ATTINY102 | 1.44 | 0.62 |
| MSP430G2252 | 1.59 | 0.67 |
| LPC822 | 1.64 | 0.75 |
| ATTINY13 | 1.84 | 0.85 |
| EFM32ZG110 | 1.36 | 1.01 |
| ATSAMD09 | 2.32 | 1.09 |
| ATTINY25 | 2.74 | 1.27 |
(prices are based off digikey as of 7/25/2016 and may change)
It's interesting to see how much processing power a dollar (or less) can buy in volume. Even light ARM cores are cheaper now than hobbyist mainstays like the ATTINY25. The microcontroller I'll probably go with is the ATTINY102, because of it's low cost. Besides, I've always worked with ATTINY chips. And lack of Arduino IDE support will provide the right amount of motivation for me to finally learn C.
The other challenge is the fact that I can't seem to find the ATTINY102 in stock anywhere on the internet. The official dev board is available, but not the actual IC. I can improvise and work with the TINY85, which I already have on hand, hoping that the 102 will go on sale or Atmel can provide me with free samples :).
Neat project, seems like a great ATtiny application. I've had good luck getting up and running fast using Adafruit's USBtinyISP along with their AVRdude command line instructions; if you haven't seen it already, the guide is an awesome way to get started programming ATtinys in C using a fully open-source toolchain: https://learn.adafruit.com/usbtinyisp/avrdude
I used to use the arduino IDE to flash fuses, but recently I was forced to learn AVRdude to finish a project. It's actually pretty intuative. However, I'll probably stick to my standby 'Arduino as ISP' setup simple because I can't be assed to get a USBtinyISP or equivalent. I supposed I could just hack a programming adapter together, but I don't have any leftover protoboard to do that with. Mabye a dedbug AVR prggrammer is the way to go ???.
qquuiinn
Also, I'm a big fan of the freeform deadbug-style construction technique!